Yeah, it can take a bit to mentally get around pushing yourself on your workouts. You'll find little tricks to help you get through. Some things I do.
Take note of 'halfway' points. "I'm halfway through my reps for this set", "I'm halfway through my sets", "I'm halfway through my workout". I find it helps to know I have less to go than I've already done.
Count reps remaining in my head. If I'm doing sets of 12, then at 9 I "only have 3 to go, 2 to go, 1 to go". It seems silly to stop when you only have a few reps remaining.
Of course there are times even tricks like that dont work, and you just have to close your eyes, grit your teeth and get them done 1 rep at a time and try to shut out the pain.
Good luck with it all, sounds like you're off to a good start
.